1. Field of the Invention
The present invention relates to a biological observation apparatus and biological observation method.
2. Description of the Related Art
Generally, when precisely observing a living body by using a biological observation apparatus, a biological vibration as the vibration of the living body to be observed poses a serious problem.
In biological observation, a living body to be observed is observed as it is dyed with any of various dyes such as a fluorescent dye or light-emitting dye. Since light from any of these dyes is very weak, an image of the living body is normally sensed by using a high-sensitivity camera.
For example, the technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2007-187810 detects the vibration of a living body as an observation target by using a vibration detecting camera having a frame rate (to be referred to as an FPS hereinafter) higher than that of a high-sensitivity camera.
Since light from a living body is weak as described above, however, the exposure time must be set to a certain long time in order to sense an image of the feature point of the living body. That is, it is necessary to decrease the FPS. This decrease in FPS makes high-accuracy control impossible. In other words, if the FPS is set at a value capable of achieving high-accuracy control, it becomes difficult to detect a biological vibration by using the feature point of the living body.
Under the circumstances, the following technique is proposed in, e.g., “Official Journal of the Society for Molecular Imaging”, vol. 5, July, 2006, abstracts, p. 240. That is, according to “Official Journal of the Society for Molecular Imaging”, vol. 5, July, 2006, abstracts, p. 240, a marker for detecting a biological vibration is attached to a living body to be observed. This makes high-accuracy biological observation and biological vibration control possible.
In the technique disclosed in non-patent reference 1 described above, however, the above-mentioned marker is taken in an observation image, as shown in FIG. 3. If an exposure time suitable for the observation of a living body is set for an observation image like this, so-called smear-blooming occurs due to a high contrast between the marker and living body.
That is, in the technique disclosed in “Official Journal of the Society for Molecular Imaging”, vol. 5, July, 2006, abstracts, p. 240, the exposure time of a high-sensitivity camera for sensing an observation image must be shortened, and this prevents precise observation.